In fact it is not entirely correct. Recent research from Johns Hopkins Medical School issued a surprising fact, caffeine was not really working can increase your cognitive performance. This study on cognitive performance improved by controlling the coffee drinking habits of the participants. In this study, the participants were tested for the people who used to enjoy 2-4 cups of caffeinated drinks which is equivalent to 200-800 mg of caffeine a day. As a result, the study found that caffeine can be addictive. When used to enjoy caffeine, so when cognitive performance and mood are down then you think that only caffeine can make you excited again. Though caffeine does not actually improve your performance, but only a return to normal levels for a short time.